It has been known in the art to check for defects in semiconductor devices such as integrated circuit (IC) devices by subjecting them to a burn-in test. In connection with such a burn-in test, the semiconductor device is mounted on a socket for connecting the device to a test piece of equipment. A commonly used socket is a pop-up type which has a cover member which moves in alternating motion from a first original position away from the main base body of the socket to a second position adjacent the main base and then back again to the first position. Such a socket with straight line movement of the cover relative to the socket base is suitable for automatic mounting of a semiconductor device.
In the main base body, a plurality of contact members is mounted. One end of each contact member protrudes from the bottom of the main socket body so as to be electrically connected with a contact on a circuit substrate while the other end is positioned to electrically connect with a terminal of a semiconductor device mounted on the main base body. On the opposing sides of the semiconductor device placing surface of the main base body, a pair of latch members is installed with each latch member rotating in linkage with the straight-line movement of the cover member. At the tip of the latch member, a pressing part is provided for holding down the semiconductor device on the placing surface of the main base body.
In such a prior art device, as the cover is pushed downward toward the base body, the latch members are rotated to a retracted position away from the placing surface for the semiconductor device. In this position, the semiconductor device can be placed on the placing surface through an opening provided in the cover member. Each terminal of the semiconductor device is positioned to be electrically connected with the other end of the socket contact members. When the cover is returned to its original position away from the main base, the latch members return to their original position so as to press against the upper surface of the semiconductor and, at the same time, bring the terminals of the semiconductor device into electrical connection with the contact members of the socket.
Such a socket has been useful in practice but due to the fact that the latch member moves in a rotating arc, the area of contact between the pressing part of the respective latch members and the upper surface of the semiconductor device is small. As a consequence, a localized stress concentration is produced by the latches on the semiconductor device which can cause breakage of such semiconductor devices, especially one of a thin type.
Reliability problems can still exist even when the pressing part of the latch member is flat. This is due to the fact that the rotary movement of the latch causes its pressing part to draw an arc shaped track which makes it difficult to make a precise contact between the flat surface of the pressing part and the upper surface of the semiconductor device.
Further, due to dimensional tolerance differences in the semiconductor devices, the upper surface of such devices is not always at a fixed height making it practically impossible to cause the pressing part of the latch member to uniformly and consistently contact the semiconductor device at all times.
Still further, since the socket is exposed to elevated temperatures (approximately 135° C.) during the burn-in test, the variance of thermal expansion of different components of the socket will make it practically impossible to cause the pressing part of the latch member to accurately contact the upper surface of the semiconductor device at a height certain at all times.